// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_GPU_AVDA_SHARED_STATE_H_
#define MEDIA_GPU_AVDA_SHARED_STATE_H_

#include "base/synchronization/waitable_event.h"
#include "gpu/command_buffer/service/gles2_cmd_decoder.h"
#include "media/base/android/media_codec_bridge.h"
#include "ui/gl/gl_bindings.h"
#include "ui/gl/gl_context.h"
#include "ui/gl/gl_image.h"
#include "ui/gl/gl_surface.h"

namespace gl {
class SurfaceTexture;
}

namespace media {

// Shared state to allow communication between the AVDA and the
// GLImages that configure GL for drawing the frames.
class AVDASharedState : public base::RefCounted<AVDASharedState> {
public:
    AVDASharedState();

    GLuint surface_texture_service_id() const
    {
        return surface_texture_service_id_;
    }

    // Signal the "frame available" event.  This may be called from any thread.
    void SignalFrameAvailable();

    void WaitForFrameAvailable();

    void SetSurfaceTexture(scoped_refptr<gl::SurfaceTexture> surface_texture,
        GLuint attached_service_id);

    // Context and surface that |surface_texture_| is bound to, if
    // |surface_texture_| is not null.
    gl::GLContext* context() const { return context_.get(); }

    gl::GLSurface* surface() const { return surface_.get(); }

    // Helper method for coordinating the interactions between
    // MediaCodec::ReleaseOutputBuffer() and WaitForFrameAvailable() when
    // rendering to a SurfaceTexture; this method should never be called when
    // rendering to a SurfaceView.
    //
    // The release of the codec buffer to the surface texture is asynchronous, by
    // using this helper we can attempt to let this process complete in a non
    // blocking fashion before the SurfaceTexture is used.
    //
    // Clients should call this method to release the codec buffer for rendering
    // and then call WaitForFrameAvailable() before using the SurfaceTexture. In
    // the ideal case the SurfaceTexture has already been updated, otherwise the
    // method will wait for a pro-rated amount of time based on elapsed time up
    // to a short deadline.
    //
    // Some devices do not reliably notify frame availability, so we use a very
    // short deadline of only a few milliseconds to avoid indefinite stalls.
    void RenderCodecBufferToSurfaceTexture(MediaCodecBridge* codec,
        int codec_buffer_index);

    // Helper methods for interacting with |surface_texture_|. See
    // gfx::SurfaceTexture for method details.
    void UpdateTexImage();
    // Returns a matrix that needs to be y flipped in order to match the
    // StreamTextureMatrix contract. See GLStreamTextureImage::YInvertMatrix().
    void GetTransformMatrix(float matrix[16]) const;

    // Resets the last time for RenderCodecBufferToSurfaceTexture(). Should be
    // called during codec changes.
    void clear_release_time() { release_time_ = base::TimeTicks(); }

protected:
    virtual ~AVDASharedState();

private:
    friend class base::RefCounted<AVDASharedState>;

    scoped_refptr<gl::SurfaceTexture> surface_texture_;

    // Platform gl texture id for |surface_texture_|.
    GLuint surface_texture_service_id_;

    // For signalling OnFrameAvailable().
    base::WaitableEvent frame_available_event_;

    // Context and surface that |surface_texture_| is bound to, if
    // |surface_texture_| is not null.
    scoped_refptr<gl::GLContext> context_;
    scoped_refptr<gl::GLSurface> surface_;

    // The time of the last call to RenderCodecBufferToSurfaceTexture(), null if
    // if there has been no last call or WaitForFrameAvailable() has been called
    // since the last call.
    base::TimeTicks release_time_;

    // Texture matrix of the front buffer of the surface texture.
    float gl_matrix_[16];

    class OnFrameAvailableHandler;
    scoped_refptr<OnFrameAvailableHandler> on_frame_available_handler_;

    DISALLOW_COPY_AND_ASSIGN(AVDASharedState);
};

} // namespace media

#endif // MEDIA_GPU_AVDA_SHARED_STATE_H_
